Image Processing Apparatus and Image Processing Method

1. An image processing apparatus for scaling an image comprising: a memory to store data representing the image; and a processor, which: determines a pixel operation position which is either a position for inserting or deleting a first pixel in accordance with a scaling ratio; inserts the first pixel or deletes the first pixel from the pixel operation position; calculates an error between a value of the first pixel and a first density representing densities of a first set of pixels located in a vicinity of the first pixel; and allocates the error to a second pixel selected from the first set of pixels, in such a manner that a value of the second pixel falls within an allowable range estimated from values of a second set of pixels near the second pixel.

2. The image processing apparatus of claim 1 , wherein the processor restricts the vicinity to an area adjacent to the first pixel in a direction of scaling.

3. The image processing apparatus of claim 1 , wherein the processor allocates the error to pixels within a predetermined area with respect to the first pixel.

4. The image processing apparatus of claim 1 , wherein the processor: allocates a first portion of the error to the second pixel; selects a third pixel from the first set of pixels; and allocates a second portion of the error to the third pixel.

5. The image processing apparatus of claim 4 , wherein the second pixel is located at a first distance from the first pixel, the third pixel is located at a second distance from the first pixel, and the second distance is greater than the first distance.

6. The image processing apparatus of claim 5 , wherein the first portion of the error is greater than the second portion of the error.

7. The image processing apparatus of claim 1 , wherein the processor estimates the allowable range using an interpolation algorithm.

8. The image processing apparatus of claim 1 , wherein the processor determines a maximum value and a minimum value of the allowable range, based on values of pixels adjacent to the second pixel.

9. A computer-implemented image processing method for scaling an image comprising steps of: determining a pixel operation position; inserting or deleting a first pixel at the pixel operation position; calculating an error between a value of the first pixel and a first density representing densities of a first set of pixels located in a vicinity of the first pixel; and allocating error to a second pixel selected from the first set of pixels in such a manner that a value, of the second pixel falls within an allowable range estimated from values of a second set of pixels near the second pixel.

10. The computer-implemented image processing method of claim 9 , further including restricting the vicinity to an area adjacent to the first pixel in a direction of scaling.

11. The computer-implemented image processing method of claim 10 , wherein the area is a one-dimensional area.

12. The computer-implemented image processing method of claim 9 , wherein the vicinity comprises a two-dimensional area adjacent to the first pixel.

13. The computer-implemented image processing method of claim 9 , further including allocating the error to pixels within a predetermined area with respect to the first pixel.

14. The computer-implemented image processing method of claim 9 , further including: allocating a first portion of the error to the second pixel; selecting a third pixel from the first set of pixels; and allocating a second portion of the error to the third pixel.

15. The computer-implemented image processing method of claim 14 , wherein the second pixel is located at a first distance from the first pixel, the third pixel is located at a second distance from the first pixel, and the second distance is greater than the first distance.

16. The computer-implemented image processing method of claim 15 , wherein the first portion of the error is greater than the second portion of the error.

17. The computer-implemented image processing method of claim 9 , further including estimating the allowable range using an interpolation algorithm.

18. The computer-implemented image processing method of claim 17 , wherein the interpolation algorithm is a spline interpolation algorithm.

19. The computer-implemented image processing method of claim 9 , further including determining a maximum value and a minimum value of the allowable range based on values of pixels adjacent the second pixel.